Such air flap devices are known in the field of the radiator grill on motor vehicles in general. The air flaps that are mounted movably on the air flap member serve to vary the flow through the flow opening as a function of its position to thereby vary by quantity the air flow flowing through the flow-through opening in driving operation of the motor vehicle. A convective cooling air flow through the flow-through opening can therefore be adapted to the cooling demand of function modules of the motor vehicle situated behind the flow-through opening in the direction of flow-through. For example, the warm-up phase of the internal combustion engine of a motor vehicle can be shortened in this way until reaching the rated operating temperature after a cold start or after a previous operating phase at a lower temperature than the rated operating temperature of the internal combustion engine. Reaching the rated operating temperature of the internal combustion engine can be monitored on the basis of the temperature of the coolant of the internal combustion engine to ascertain approximately whether the coolant temperature is above or below a predetermined threshold temperature.
By shortening the warm-up phase of the internal combustion engine, the period of time during which the internal combustion engine is operated with transient, and therefore suboptimal operating parameters can be shortened. During the warm-up phase the internal combustion engine usually emits a larger amount of pollutants in comparison with its operation at the rated operating temperature—per unit of time and/or per distance traveled.
Since the air flap device thus influences the pollutant emissions of a motor vehicle, it is desirable to be able to monitor its operational readiness and/or proper functioning.